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The only widely proposed screening procedure for skin cancer is visual examination of the skin, including both self-examination and clinical examination.

Benefits

In asymptomatic populations, the effect of visual skin examination on mortality from nonmelanomatous skin cancers is unknown. Further, the evidence is inadequate to determine whether visual examination of the skin in asymptomatic individuals would lead to a reduction in mortality from melanomatous skin cancer.

Magnitude of Effect: Not applicable (N/A).

Study Design: Evidence obtained from a single case-control study.

Internal Validity: Poor.

Consistency: N/A.

External Validity: N/A.

Harms

Based on fair though unquantified evidence, visual examination of the skin in asymptomatic individuals may lead to unavoidable increases in harmful consequences. These include complications of diagnostic or treatment interventions (including extensive surgery) and the psychological effects of being labeled with a potentially fatal disease. Another harmful consequence is overdiagnosis leading to the detection of biologically benign disease that would otherwise go undetected, and the possibility of misdiagnosis of a benign lesion as malignant.

Consistency: Multiple studies; small number of participants—no consistency.

External Validity: Fair.

Description of the Evidence

Background

Incidence and mortality

There are three main types of skin cancer:

Basal cell carcinoma.

Squamous cell carcinoma (together with basal cell carcinoma, this is referred to as nonmelanoma skin cancer).

Melanoma.

Basal cell carcinoma and squamous cell carcinoma are the most common forms of skin cancer but have substantially better prognoses than the less common, generally more aggressive melanoma.

Nonmelanoma skin cancer is the most commonly occurring cancer in the United States. Its incidence appears to be increasing in some [1] but not all [2] areas of the United States. Overall U.S. incidence rates have likely been increasing for a number of years.[3] At least some of this increase may be attributable to increasing skin cancer awareness and resulting increasing investigation and biopsy of skin lesions. A precise estimate of the total number and incidence rate of nonmelanoma skin cancer is not possible, because reporting to cancer registries is not required. However, based on Medicare fee-for-service data extrapolated to the U.S. population, it has been estimated that the total number of persons treated for nonmelanoma skin cancers in 2012 was about 3,000,000.[4,5] That number would exceed all other cases of cancer estimated by the American Cancer Society for that year, which was about 1.6 million.[6]

Melanoma is a reportable cancer in U.S. cancer registries, so there are more reliable estimates of incidence than is the case with nonmelanoma skin cancers. In 2016, it is estimated that 76,380 individuals in the United States will be diagnosed with melanoma and approximately 10,130 will die of it. The incidence of melanoma has been increasing for at least 30 years; however, data over the past 5 years indicate that rates are declining or plateauing among individuals younger than 50 years.[5] From 2008 to 2012, incidence rates declined by about 3% per year in both men and women aged 20 to 29 years. In contrast, among adults aged 50 years and older, the incidence rate has increased by 2.6% per year since 1996. Mortality rates have been declining by 2.6% per year since 1986 in individuals younger than 50 years, and mortality rates have been increasing by 0.6% per year since 1990 among individuals 50 years and older.[5]

A study of skin biopsy rates in relation to melanoma incidence rates obtained from the Surveillance, Epidemiology, and End Results Program (SEER) of the National Cancer Institute indicated that much of the observed increase in incidence between 1986 and 2001 was confined to local disease and was most likely caused by overdiagnosis as a result of increased skin biopsy rates during this period.[7] Between 1998 and 2007, a 2.5% relative yearly incidence increase in pediatric melanoma was observed in SEER databases. During that time, the average annual incidence in this group was exceptionally low, however (5.4 per 1 million), and may have resulted in spurious trends; nevertheless, similar trends have been seen in Sweden.[8] In the U.S. study of pediatric melanoma, nearly one-half of the patients had local disease (22% of patients had in situ disease and 25% of patients had superficial spreading), and nearly one-half of the patients had disease with a thickness of less than one millimeter. Given that mortality from pediatric melanoma had been fairly stable during those years,[9] it is likely that the increase in incidence could be explained, at least in part, by overdiagnosis.

Risk Factors

Epidemiologic evidence suggests that exposure to UV radiation and the sensitivity of an individual's skin to UV radiation are risk factors for skin cancer, although the type of exposure (high-intensity and short-duration vs. chronic exposure) and pattern of exposure (continuous vs. intermittent) may differ among the three main types of skin cancer.[10,11,12] In addition, the immune system may play a role in pathogenesis of skin cancers. Organ-transplant recipients receiving immunosuppressive drugs are at elevated risk of skin cancers, particularly squamous cell cancers (SCC). Arsenic exposure also increases the risk of cutaneous SCC.[13,14]

The incidence of melanoma rises rapidly in Caucasians after age 20 years. Fair-skinned individuals exposed to the sun are at higher risk. Individuals with certain types of pigmented lesions (dysplastic or atypical nevi), with several large nondysplastic nevi, with many small nevi, or with moderate freckling have a twofold to threefold increased risk of developing melanoma.[15] Individuals with familial dysplastic nevus syndrome or with several dysplastic or atypical nevi are at high (>fivefold) risk of developing melanoma.[15]

Accuracy of Making a Clinical Diagnosis of Melanoma

A systematic review of 32 studies that compared the accuracy of dermatologists and primary care physicians in making a clinical diagnosis of melanoma concluded that there was no statistically significant difference in accuracy. However, the results were inconclusive, owing to small sample sizes and study design weaknesses.[16] In addition, differentiating between benign and malignant melanocytic tumors during histologic examination of biopsy specimens has been shown to be inconsistent even in the hands of experienced dermatopathologists.[17] This fact undermines results of studies examining screening effectiveness and also may undermine the effectiveness of any screening intervention. Furthermore, this suggests that requesting a second opinion regarding the pathology of biopsy specimens may be important.[17]

Evidence of Benefit Associated With Screening

More than 90% of melanomas that arise in the skin can be recognized with the naked eye. Very often there is a prolonged horizontal growth phase during which time the tumor expands centrifugally beneath the epidermis but does not invade the underlying dermis. This horizontal growth phase may provide lead time for early detection. Melanoma is more easily cured if treated before the onset of the vertical growth phase with its metastatic potential.[18]

The probability of tumor recurrence within 10 years after curative resection is less than 10% with tumors less than 1.4 mm in thickness. For patients with tumors less than 0.76 mm in thickness, the likelihood of recurrence is less than 1% in 10 years.[19]

A systematic review of skin cancer screening examined evidence available through mid-2005 and concluded that direct evidence of improved health outcomes associated with skin cancer screening is lacking.[20]

However, this does not mean that skin cancers (whether melanoma or nonmelanoma) are unimportant or can be neglected without adverse consequences. When neglected, skin cancers can be disfiguring and/or cause death. Skin cancers are easily detected clinically and are often cured by excisional biopsy alone.

Various observational studies exploring the possibility that melanoma screening may be effective have been reported. An educational campaign in western Scotland, promoting awareness of the signs of suspicious skin lesions and encouraging early self-referral, showed a decrease in mortality rates associated with the campaign.[21] In northern Germany, one region that received a skin cancer screening program during 2003 and 2004 was compared with four nearby regions that received no skin cancer screening program.[22,23] The two-stage skin cancer screening program began with a total-body visual examination of the skin by a general practitioner; if skin cancer was suspected, the patient was re-examined by a dermatologist. Nineteen percent of all those eligible were screened. The melanoma mortality rates were decreased in the years after the screening program in the screened region (1.7 per 100,000 in 1998–1999 to 0.9 per 100,000 in 2008–2009), whereas the melanoma mortality rates either stayed the same or increased in the comparison regions. Because of numerous methodological limitations such as the lack of randomization, lack of an internal control group, and relying on the region-level data rather than individual-level data to assess outcomes, these data provide only very weak evidence that the screening program reduced mortality from melanoma. Further, a thorough consideration of the harms was not provided, such as the harms associated with false-positive tests and overdiagnosis. (Refer to the Evidence of Harm Associated With Screening section in the Description of the Evidence section of this summary for more information.) Of note, four out of five skin lesions excised in the screening program were found to be benign.[22,23]

A population-based trial using cluster randomization to determine the effect of skin screening on melanoma mortality was initiated in Queensland, Australia.[24] Intervention communities were randomly assigned to receive a 3-year program targeting adults older than age 30 years. The program consisted of:

Community education and promotion of self-screening.

General practitioner education about screening and training in the diagnosis of melanoma.

Free skin cancer screening clinics.

Matched control communities received usual care. Originally designed to include 44 matched communities followed for 15 years, the trial lost its funding after its initial pilot phase in 18 communities (population 63,035).[25] Although the pilot phase established feasibility of community-based programs, no health outcomes were reported. In the study, 16,383 whole-body skin examinations were reported in the intervention communities, resulting in a referral rate of 14.1% (18.2% for people aged 50 years or older). Thirty-three melanomas were diagnosed, 13 of which were in situ. The estimated specificity for melanoma was 86.1%, with a positive predictive value (PPV) of 2.5%. The PPVs for squamous cell and for basal cell cancers were 7.2% and 19.3%, respectively. Negative screens were not followed up, and the sensitivity of skin examination was not reported.[26]

Evidence of Harm Associated With Screening

Harms have not been well studied or reported in quantitative terms. However, visual examination of the skin in asymptomatic individuals may lead to unavoidable adverse consequences. These include complications of diagnostic or treatment interventions (including extensive surgery) and the psychological effects of being labeled with a potentially fatal disease. Another harmful consequence is overdiagnosis leading to the detection of biologically benign disease that would otherwise go undetected and the possibility of misdiagnosis of a benign lesion as malignant. (Refer to the Accuracy of Making a Clinical Diagnosis of Melanoma section of this summary for more information.)

Updated statistics with estimated new cases and deaths for 2016. Also revised text to state that the incidence of melanoma has been increasing for at least 30 years; however, data over the past 5 years indicate that rates are declining or plateauing among individuals younger than 50 years. Also added text to state that from 2008 to 2012, incidence rates declined by about 3% per year in both men and women aged 20 to 29 years; in contrast, among adults aged 50 years and older, the incidence rate has increased by 2.6% per year since 1996; and mortality rates have been declining by 2.6% per year since 1986 in individuals younger than 50 years, and mortality rates have been increasing by 0.6% per year since 1990 among individuals 50 years and older.

This summary is written and maintained by the PDQ Screening and Prevention Editorial Board, which is editorially independent of NCI. The summary reflects an independent review of the literature and does not represent a policy statement of NCI or NIH. More information about summary policies and the role of the PDQ Editorial Boards in maintaining the PDQ summaries can be found on the About This PDQ Summary and PDQ® - NCI's Comprehensive Cancer Database pages.

About This PDQ Summary

Purpose of This Summary

This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about skin cancer screening. It is intended as a resource to inform and assist clinicians who care for cancer patients. It does not provide formal guidelines or recommendations for making health care decisions.

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